The proposal is to study children's use of planning knowledge in situations of personal and social significance. What children known and can apply about plans is studied in hypothetical but relevant practical and social settings and by convergent methods on how planning sequences are formulated, executed, and represented. Children are asked in different tasks to observe, understand, narrate, formulate, explain, produce, retrieve alter, repair, and learn plans where the planning sequences unfold over time or after they have been experienced. The social and personal contexts in which children are asked to plan are selected so as to be representative of problems and changes in goal states that children experience and about which they have knowledge. Adhering to a theory of intentional action that views plans as sequences of goal-directed actions, a model of analysis of discourse that can identify planning components and how they are organized in a representation is used. This analysis yields qualitative and quantitative measures on planning components and relations for comparisons of similarities and differences in developmental and individual planning knowledge and skill. The key assessment is on whether children know how to attain and maintain goals that ensure survival and well-being. To known this means that children can detect changes in conditions that affect their ability to attain or maintain their goals or that cause failure. It also means that they understand the causal implications of succeeding or failing in goal attainment, that they formulate plans of action contingent upon failure or success, and that they translate plans into action and evaluate outcomes of the actions. These skills are measured across the several tasks by a model that provides explicit criteria for identifying and representing them where children actively formulate and produce planning sequences. Developmental and individual differences and similarity in these skills are this made possible and the convergent methods allow for determining their generality.